1. Field of the Invention
The present invention relates to a boot positioning apparatus for positioning protective boots at predetermined locations on a constant velocity joint assembly prior to winding thereon of fastening bands, and a transfer pallet adaptable to various types of constant velocity joint assembly. The present invention also relates to an apparatus for automatically setting a vertical position of a constant velocity joint assembly, a loader apparatus adaptable to various types of constant velocity joint assembly, and a boot positioning apparatus capable of positioning boots on drive shafts of various different diameters.
2. Description of the Related Art
In Japanese Patent Laid-open publication No. HEI-2-76649, the assignee of the present application discloses an invention entitled "Apparatus for fixedly attaching protective boot to a central drive shaft and drive shaft positioning apparatus for use therein", which will be outlined below with reference to FIG. 37 (corresponding to FIG. 15 of the Japanese publication).
Constant velocity joint assembly 500 shown in FIG. 37 comprises a relatively long, flexible central drive shaft 501, a Birfield constant-velocity ball joint 502 and tripod constant-velocity ball joint 520 coupled to both ends of the drive shaft 501, and a damper weight 515 mounted on a central portion of the drive shaft 501.
The Birfield constant-velocity ball joint 502 coupled to the one end of the central drive shaft 501 includes an outer ring 504 that is constructed of integrally-formed cup and shaft portions 505 and 506. In the outer ring 504, there are received a plurality of balls 507 forming a ball bearing, a retainer 508 and an inner ring 509. The ball joint 502 is a constant velocity universal joint which, even when some intersecting angle exists between the central drive shaft 501 and the shaft portion 506, can transmit torque by coupling one end of the shaft 501 with the inner ring 509 through male (external) and female (internal) splines (spline coupling). As well known in the art, the balls 507 has to be greased, and a protective boot 511 in the form of a bellows-like rubber cover is mounted to prevent leakage of the grease and entry of alien substances from the outside. Reference numerals 512 and 513 denote fastening bands that are firmly wound around the cup portion 505 and central drive shaft 501 to fixedly attach the axial ends of the boot 11 thereto. The damper weight 515 is also fixed to the central drive shaft 501 by means of a band 516.
The tripod constant-velocity ball joint 520 coupled to the other end of the central drive shaft 501 includes an outer ring 521 that is constructed of integrally-formed cup and shaft portions 522 and 523, and a Y-shaped member 525 having three leg portions (only one of the leg portions is shown in the figure). Three axial grooves 524 are formed in the inner surface of the outer ring 521, and a roller bearing 526 is provided around each of the leg portions and slidably fitted in a corresponding one of the grooves 524. In the ball joint 520, the central drive shaft 501 is spline-coupled at one end to the Y-shaped member 525 so as to permit axial movement of the outer ring 521 relative to the central drive shaft 501. Reference numeral 527 denotes a protective boot, and 528 and 529 denote fastening bands that are firmly wound around the cup portion 522 and central drive shaft 501 to fix the axial ends of the boot 527 thereto.
FIG. 38 is a view showing boot-fixing operations of the disclosed apparatus.
Arrow (1): Constant velocity joint assembly 500a placed on a workpiece seat 531 at the downstream end of a conveyor 530 is lifted by a first loader apparatus 532. At this stage, protective boots have just been attached incompletely or provisionally with no fastening bands wound thereon.
Arrow (2): The first loader apparatus 532 is moved laterally to transfer the constant velocity joint assembly 500a onto a positioning apparatus 533, where each of the boots is properly positioned at a predetermined location.
Arrow (3): The constant velocity joint assembly 500a with the properly positioned boots is lifted by a second loader apparatus 534.
Arrow (4): The constant velocity joint assembly 500a being lifted by the second loader apparatus 534 is horizontally turned by 90.degree. and moved downstream by means of the loader apparatus 534 as shown by arrow (5).
Arrow (6): The constant velocity joint assembly 500a is lowered by means of the second loader apparatus 534 until it is placed on a transfer jig 535.
Arrow (7): The transfer jig 535 with the constant velocity joint assembly 500a placed thereon is moved a predetermined distance along a horizontal rail 536.
Arrow (8): The transfer jig 535 is positioned at a predetermined location in a first work station, and the constant velocity joint assembly 500a is then raised to a predetermined vertical position where a fastening band 512 is wound by a first band winding apparatus 537 on a large-diameter portion of the boot of the Birfield constant-velocity ball joint 502.
Then, in a similar manner, another fastening band 513 is wound by a second band winding apparatus 538 on a small-diameter portion of the second joint. After this, another fastening band 529 is wound by a third band winding apparatus 539 on a small-diameter portion of the first joint and still another band 528 is wound by a fourth band winding apparatus 540 on a large-diameter portion of the first joint. Further, still another band 516 is wound on the damper weight 515 by a fifth band winding apparatus 541.
After the winding of the band 516, the constant velocity joint assembly 500a is picked up from the transfer jig 535 by a third loader apparatus (not shown), and the thus-emptied transfer jig 535 is returned to the initial position by means of a return conveyor. The third loader apparatus holding the constant velocity joint assembly 500a is moved along a guide rail to transfer the joint assembly 500a onto a delivery conveyor. Namely, the constant velocity joint assembly 500a is unloaded from the transfer jig 535 and transferred downstream, while the emptied transfer jig 535 is returned upstream by means of the return conveyor.
As a result of the foregoing operational steps, the constant velocity joint assembly 500a with the boots provisionally attached in incomplete conditions becomes the constant velocity joint assembly 500 where each of the boots is fixed at the predetermined position with the fastening bands firmly wound at the axial opposite ends of the boot.
As disclosed in the 2-76649 publication, the positioning apparatus 533 has a right base plate slidably mounted on a base of the apparatus, a slide table slidably mounted on the base plate, and a first unit slidably mounted on the slide table. The right base plate has one more component part than a left base plate, which, in order to adapt to various types (especially, various different lengths) of constant velocity joint assembly 500 (500a), allows the right base plate to move in the leftward/rightward direction in response to a human operator manually operating a predetermined handle provided at the right end of the apparatus 533.
However, with the disclosed positioning apparatus 533, the predetermined handle needs to be adjusted by the human operator to deal with a change in the type of constant velocity joint assembly 500 (500a), which is very bothersome. Although the disclosed technique is suited for cases where the type of constant velocity joint assembly 500 (500a) to be constructed is not changed frequently, it can never be suitable for production of many types of constant velocity joint assembly. Further, because a first damper provided in the middle of the apparatus is mounted on the left slide table, the central drive shaft would be clamped at a portion away from its center, which would result in a difference in positioning accuracy of the left and right boots. In addition, the right base plate can be stopped only at a limited number of positions because only a limited number of proximity switches are provided to monitor a position of the right base table. Thus, in cases where it is desired to stop the right base table at many desired positions, many proximity switches need to be provided, so that the layout of the proximity switches would become very complicated and the switches would break down frequently.
The transfer jig 135 disclosed in the 2-76649 publication includes three dampers for gripping a right end, center and left end of a constant velocity joint assembly. Although the right and central dampers are slidably mounted on respective guide rails in order to handle or adapt to a plurality of types of constant velocity joint assembly, it is absolutely necessary for a human operator to manually loose a locking lever to permit the sliding movement of these dampers and then again tighten the locking lever. However, such manual operations of the locking lever are very cumbersome particularly in cases where the constant velocity joint assembly is frequently switched from one type to another. In other words, the disclosed technique is suited only for cases where the constant velocity joint assembly type is rarely switched and thus can not be suitable for production of multiple types of constant velocity joint assembly.
The 2-76649 publication also discloses an "apparatus for positioning a constant velocity joint assembly", which will be described below with reference to FIGS. 39A to 39C. FIG. 39A is a side view of a positioning apparatus 550, in which a lifter 551 raises an actuator arm 552 (denoted by a phantom line) to press the arm 552 against an upper stopper 553. FIG. 39B is a front view of the positioning apparatus 550, which shows that two stoppers 553 and 554 having different heights can be laterally moved by manually rotating a locking handle 555 in such a way that only one of the stoppers 553 or 554 is positioned immediately above the lifter 551. Further, FIG. 39C shows the actuator arm 552 raised by the lifter 551 and pressed against the upper stopper 553, and it is in this position that welding of the fastening bands are conducted.
However, to deal with every change in the type of constant velocity joint assembly 500 (500a), the stoppers 553 and 554 must be repositioned by manually rotating the locking handle 555 in the positioning apparatus 550, which is very bothersome. Although the disclosed technique is suited for cases where only two types of constant velocity joint assembly 500 (500a) are handled and switching between the types does not frequently take place, it can never be suitable for production of multiple types of constant velocity joint assembly. If the number of such stoppers is increased, the entire size of the apparatus will unavoidably become greater.
Further, as disclosed in the 2-76649 publication, the second loader apparatus includes three dampers for gripping the constant velocity joint assembly, and these dampers are adjustable in position. The first and third loader apparatuses are constructed in the same way as the second loader apparatus. The positional adjustment in the loader apparatuses has to be conducted manually, and thus these loader apparatus are suited only for such cases where the joint assembly type switching does not take place often and are never suited for production of multiple types of constant velocity joint assembly.
The same assignee also proposed, in Japanese Patent Laid-open Publication No. HEI-4-201132, an apparatus which is designed to accurately position the ends of the boots at the ends of the central drive shaft as outlined in FIG. 40. In FIG. 40, the boot positioning apparatus 600 includes a pair of opposed leg portions 602 extending from a slider 601, on each of which is swingably mounted a pressing member 603. Each of the pressing members 603 is normally biased via a coiled tension spring 604 to an open position. FIG. 40 shows the apparatus 600 with the pressing members 603 lightly gripping a shaft 605. The inner gripping portions of the pressing members 603 must have a same curvature as the outer peripheral curvature of the shaft 605. However, today, situations often arise where the same boot positioning apparatus 600 has to handle a variety of shafts 605 of different diameters. Every time the workpiece to be handled is changed to another one of different outer peripheral curvature, the pressing members 603 must be replaced with others having corresponding curvature. Thus, many pressing members of different sizes must be produced by lots for each size and stocked for subsequent use. As a result, the boot positioning apparatus 600 required a substantial time and steps to adapt to many types of workpiece or constant velocity joint assembly and thus can not properly deal with production of multiple types of constant velocity joint assembly.